I do not have SSD's, it is on one of my "to do" lists soon after I find a pile of cash in a desk at someones garage sale... heh.
As I understand it from reading up on other folk's experience and opinions though, SSD can crap out at any time and with no warning, Most folks recommend keeping your important files on a regular drive... or at least back ups.
As I understand it as well, moving EQ/MQ to the SSD will save a large amount of wear and tear from your regular HD, depending on how many toons you usually run. The constant read/write (depending on what your toons are doing) keeps the HD highly active. the SSD of course wont have as much issue with this.
That being said, since performance with the rest of the EQ machines is a moot thing... I would say just load EQ on those machines. As Jimbob noted, they will take longer to reboot... but if all they do is EQ, no biggie there.
The main machine how ever, sorta depends on what else you do with it and what kind of gambling man you want to be. A SSD can get you close to a 4-10 second start up, and help speed up a number of other operations (a few instances they actually run slower, but that is uncommon) so there is some reason to give though into putting your OS on the SSD. If so, I would look into a dualboot, or simply unplug your regular drive and install on the SSD...then plug the regular HD back in.... so you will have a back up OS already installed. To save what hair you have left later on if something happens =) (there is no playing EQ with out the occasional hair pulling =P) I am sure the tech heads have a better optiont hen that.... sort of a redneck way of doing it... but it works.